Feeding mechanism for sewing machines



Jan. 7, 1941. P. J. ANTON FEEDING MECHANISM FOR SEWING MACHINES Filed May 20, 1939 WA mew ?W 7 Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE FEEDING MECHANISM FOR SEWING MACHINES Application May 20, 1939, Serial No. 274,727

4 Claims.

' This invention relates to improvements in sewing machines, and more particularly to a construction of feed-dogs for differential or gathering feeding mechanism embodying two feed-dogs which are given difierential movements relative to each other.

In prior machines of the type disclosed in the patents to A. Grieb, No. 933,033, dated Aug. 31, 1909, and N. Knaus, No. 2,052,408, dated Aug. 25, 1936,,it has been found that when sewing knitted goods, or rayon and similar flimsy materials, the differential action of the main and auxiliary feeddogs results in the crowding of the work into the gap between the toe of the main feed-dog and the heel of the auxiliary feed-dog. The. subsequent feeding of the work from between the feed-dogs frequently causes the individual threads in the work to become snared on the toe of the main feed-dog, thereby distending and breaking the thread snared upon the feed-dog adjacent the seam line. In knitted goods and the like, a broken thread adjacent the seam line results in a so-called run, and its presence in a garment renders the same practically Worthless.

The primary object of the present invention is to obviate injury to the work, suchas the distention of thread-loops adjacent the seam line in knitted goods and the breaking of individual threads in rayon and similar flimsy materials, caused by the crowding of the work between the main and auxiliary feed-dogs resulting from the differential action of the dog-s.

Several other objects and features of the present invention will be clearly understood from the following description and accompanying drawing, in which:

Fig. 1 is a top plan View, partly in section, showing one form of my improved construction of feed-dogs embodied therein.

Fig. 2 is -a sectional View .taken substantially along the line 2-2, Fig. 1.

Fig. 3 is an enlarged View, in elevation, showing the presser-foot, work and feed-dogs in their positions during normal sewing.

Fig. 4 is a perspective view of the main feeddog and the auxiliary feed-dog.

As illustrated in the drawing, my improved construction of feed-dogs is shown as applied to the diiferential feeding mechanism disclosed and claimed in the above mentioned patent to N. Knaus, No. 2,052,408. In the embodiment chosen for illustration purposes only, the bed I of the machine is provided with suitable bearings in which is journaled a main-shaft 2, and rearwardly extending bearing supports 3 formed with suitable bearing a'perturesto receive the feedrock-s'haft 4.

Fixed upon the rock-shaft 4 is a feed-rocker 5 having two spaced lateral arms 6 and I, each arm having an apertured end which'receives a pivot-pin 8. The feed-rocker 5 receives an oscillatory movement from the main-shaft 2 by means of a pitman 9 having one of its ends embracing an adjustable eccentric 10 on the main-shaft, and its other end connected by a pivot-pin II to a depending arm I2 which has its split hub l3 secured to the feed-rocker 5.

Disposed intermediate the arms 6 and 1 of the feed-rocker 5 and carried by the pivot-pin 8 is the enlarged apertured end I4 of the auxiliary feed-bar l5 which carries on its forwardly projecting end I6 an auxiliary feed-dog H. A main feed-bar i8 is slidably carried on the auxiliary feed-bar l5, the main feed-bar being provided with a rib l9 which enters a channel 20 in the auxiliary feed-bar and a longitudinal aperture 2| which receives a stud 22 carried by the auxiliary feed-bar |5.- It will be understood that the above described connection permits the main feed-bar to be reciprocated on the auxiliary feed-bar and independently thereof, but connected thereto, so as to bemoved upand down therewith. The forward end of the main feed-bar l8 carries a main feed-dog 23 which is located in rear of and substantially in alignment with the auxiliary feeddog l1.

From Fig. 2 it will be observed that the auxiliary feed-bar 15 overhangs the usual feed-lift eccentric 24 on the main shaft 2 and a short upstanding vpitman 25 embracing the feed-lift eccentric is pivotally connected to the auxiliary feed-bar It by means of a pivot stud 26 carried by the pitman 25. Through this connection with the main-shaft, the feed-bars receive their rising and falling movement.

To impart a variable throw to the main feeddog 23 relative to the auxiliary feed-dog H, the main feed-bar I8 is connected by a link 21 to a belt-crank lever 28 which is pivotally secured to the rocker-arm 1 by a pivot-stud 2-9. The lever 28 is formed with a rearwardly projecting thumbpiece 30 and a locking lever 3| is pivotally secured to the member 28 by the pivot-stud 32. The above described means for varying the throw of the main feed-dog is identical with that forming the subject of the above mentioned patent to Kna-us, No. 2,053,408, to which reference may be had for a more detailed and comprehensive description.

Referring now to Figs. 1 and 4, it will be seen that the auxiliary feed-dog I1 is preferably formed with two serrated sections 33 and 34. The heel 34 of section 34 is recessed longitudinally thereof to provide a clearance opening 35, see Fig. 4, into which projects the extended toe 36 of the serrated section 31 on the main feeddog 23. The work-engaging surface of the extended toe 36 is smooth, as distinguished from the serrated surface of the heel 34 of the auxiliary feed-dog II. By reference to Fig. 1 it will be understood that the interfitting portions of the feed-dogs, in effect, constitute a single feedmember having no substantial gap between the component parts thereof into which the material may be crowded. The extended toe 36 is formed with the fiat work-supporting surface so that, when operating upon flimsy materials, that portion of the work W clamped between the toe 36 of the main feed-dog 23, the heel 34' of the auxiliary feed-dog l1 and the usual presser-foot 38 may move or slip relative to the toe 36 of the main feed-dog under the gripping action of the serrated heel 34' of the auxiliary feed-dog which at this portion of the feed-stroke is moving faster than the adjacent main feed-dog 23.

It has been discovered that if the interfitting portions of the auxiliary and main feed-dogs are both serrated, the resulting positive gripping of the material by the two feed-dogs, at the time the differential action between the two dogs is at a maximum, causes an excessive tensioning of the material at the point of overlapping of the feed-dogs with the result that certain of the threads in the material are stretched and broken adjacent the seam line.

With the present improvement, it can be appreciated that the work W which is gripped between the overlapped sections 34 and 36 of the feed-dogs on one side of the work and the press- 40 er-foot at on the other side of the work is not stretched excessively at the time the difierential action between the two feed-dogs is at a maximum because the smooth surface of the extended toe 36 does not positively grip the work, but

permits it to slip when the tension on the work exceeds a certain limit.

From the above description, it will be understood that the present invention is designed to eliminate injury to the work and permit the machine to be operated at a high rate of speed with a minimum of defective work.

Having thus set forth the nature of this invention what I claim herein is:

1. A sewing machine differential feeding mechanism including a main feed-dog and an auxiliary feed-dog, and means for actuating said feed-dogs differentially, said feed-dogs having interfitting sections for elimination of a gap between said feed-dogs, one of said interfitting sections having a serrated work-engaging surface and the other interfitting section having a smooth work-engaging surface.

2. A sewing machine differential feeding mechanism including a main feed-dog and an auxiliary feed-dog arranged in tandem and adapted to engage the same side of the work, and means for actuating said feed-dogs difi'erentially, said feed-dogs having their adjacent end-portions in overlapping relation, one of said overlapping end-portions having a serrated work-engaging surface and the other of said overlapping end-portions having a smooth work-engaging surface.

3. A sewing machine defferential feeding mechanism including a main feed-dog and an auxiliary feed-dog arranged in tandem and adapted to engage the same side of the work, and means for actuating said feed-dogs difierentially, said auxiliary feed-dog having the heel thereof recessed, and said main feed-dog provided with an extended toe adapted to be received in said recess so that the gap between the feed-dogs is substantially closed to prevent the crowding of work therebetween.

4. A sewing machine differential feeding mechanism including a main feed-dog and an auxiliary feed-dog arranged in tandem and adapted to engage the same side of the work, and means for actuating said feed-dogs differentially, said auxiliary feed-dog haw'ng the heel of the work-engaging surface thereof recessed, and said main feed-dog provided with an extended toe adapted to be received in said recess so that the gap between the feed-dogs is substantially closed to prevent the crowding of work therebetween, the heel of the auxiliary feed-dog being serrated and the toe of the main feed-dog being smooth.

PERCIVAL J. ANTON. 

